Top-down

The basement, including the core, will be constructed from the ground floor down at the same time as the 80-storey structure is constructed from the ground floor up.

While the basement is being constructed, the superstructure core will be supported by large braced plated plunge columns 500mm x 500mm square. The columns weigh around 800kg/m and will carry around 19MN each.

When the three storey basement excavation is complete, the columns will be embedded in the insitu concrete core walls for added strength. The columns will be held in place at ground level by a 2.6m tall initial section of core, which also acts as the starting point for the slipforming of the above ground section of the core.

Designer WSP Cantor Seinuk shunned the traditional method of building the core up from the basement because it was slow. “We were intending to build the core bottom up, but it was taking too long,” said WSP Cantor Seinuk director Kamran Moazimi. “Instead we’re going for a top down strategy including the core.”

Top-down construction for basements from ground level is a common design solution for constrained sites where storage is an issue.On the Shard, following the installation of the piles and basement plunge columns, the ground floor slab will be built, creating a surface for the storage of materials while construction of the basement continues beneath.

The tower is being built by contractor Mace and is designed by architect Renzo Piano and structural engineer WSP Cantor Seinuk. Piling for the project started on site last week.

Have your say

You must sign in to make a comment.